The present invention relates generally to plasma arc torches and more particularly to devices and methods for operating a plasma arc torch in different operating modes.
Plasma arc torches are commonly used for cutting, marking, gouging, and welding metal workpieces by directing a high energy plasma stream consisting of ionized gas particles toward the workpiece. The plasma arc torch is typically connected to a power supply that provides both gas and electric power for operation of the plasma arc torch and is operable through a trigger disposed within a torch handle for activation of the gas and the electric power. Because the plasma arc torch creates intense localized heating at relatively high plasma exit velocities, inadvertent operation of the trigger could result in a risk of personal injury and/or damage to surrounding objects.
To reduce the risk of inadvertent torch ignition, control systems and devices are commonly provided in plasma arc torches of the known art. For example, control systems are provided within some known art power supplies, which are often at a remote location relative to the operator, to initiate or terminate gas flow to the plasma arc torch. However, such control systems require the operator to either look away from the torch or the workpiece where an operation is being performed or delay operations in order to manipulate the gas flow. Accordingly, the use of gas control systems within the power supply is somewhat inefficient and increases the risk of inadvertent torch operation. In addition to control systems, control circuits are also known that isolate current flow to the torch until gas flow is initiated. Further, audible warnings are provided in some known systems to notify the operator that the torch is ready for operation so that the torch is not improperly used.
Additionally, activation of gas flow only, i.e. no electric power, is often advantageous in certain applications such as for cooling torch components, (e.g., electrode, tip), or the workpiece. However, many plasma arc devices do not provide for a gas only mode of operation, and those that do provide for such a mode require the operator to initiate and terminate the gas flow at the power supply, not local to the plasma arc torch where operations are being performed. As a result, operation of a gas only mode is relatively time consuming and cumbersome in plasma arc torch systems of the known art.
Inadvertent torch operation may also occur when the trigger is prematurely depressed by the operator while the torch is being positioned for operation. The trigger may also be inadvertently depressed when the torch is being disassembled for maintenance or when being placed down onto a surface or object that causes the trigger to be depressed. Accordingly, devices have been provided with plasma arc torch triggers of the known art to reduce the risk of inadvertent torch operation through engagement of the trigger. One known trigger system provides a safety member to prevent inadvertent operation of the torch, wherein the operator must reposition the safety member in order to depress the trigger. Unfortunately, engagement of the safety member requires increased manual dexterity of the operator (generally wearing gloves) to engage the trigger for operation of the plasma arc torch, which is often cumbersome and time consuming when the plasma arc torch is continually being ignited and turned off.
Accordingly, a need remains in the art for a device and method that provides gas control local to the torch and operator, and which provides for multiple operating modes to control the gas flow separate from the electric power. A further need exists for a device and method that reduces the risk of inadvertent torch operation and that requires less manual dexterity than trigger systems of the known art.
In one preferred form, the present invention provides an apparatus for delivering gas and electric power to a plasma arc torch that comprises a selector with at least a first operating position and a second operating position. The first operating position operates the apparatus in a first mode to deliver gas to the plasma arc torch, and the second operating position operates the apparatus in a second mode to deliver gas and electric power to the plasma arc torch. Further, the selector may further comprise a neutral position for selecting a neutral mode in which delivery of gas and electric power to the plasma arc torch is inhibited.
As used herein, a plasma arc apparatus, whether operated manually or automated, should be construed by those skilled in the art to be an apparatus that generates or uses plasma for cutting, welding, spraying, gouging, or marking operations, among others. Accordingly, the specific reference to plasma arc cutting torches or plasma arc torches herein should not be construed as limiting the scope of the present invention. Furthermore, the specific reference to providing gas to a plasma arc torch should not be construed as limiting the scope of the present invention, such that other fluids, e.g. liquids, may also be provided to the plasma arc torch in accordance with the teachings of the present invention.
In another form, a trigger system for use in a plasma arc torch is provided that operates a selector among one or more of a first operating position, a second operating position, and a neutral position. The first operating position operates the trigger system in a first mode to deliver gas to the plasma arc torch, the second operating position operates the trigger system in a second mode to deliver gas and electric power to the plasma arc torch, and the neutral position operates the trigger system in a neutral mode in which delivery of gas and electric power to the plasma arc torch is inhibited.
In another form of the present invention, a plasma arc torch is provided that comprises a gas control device and a housing disposed within a torch handle, wherein the housing is operable with the gas control device. Further, the plasma arc torch comprises a power switch disposed within the torch handle and a selector disposed within the housing, wherein the selector is operable with the power switch. Accordingly, the selector is operable to a first operating position such that the housing activates the gas control device, thereby operating the plasma arc torch in a first mode to deliver gas to the plasma arc torch. Moreover, the selector is operable to a second operating position such that the selector activates the power switch, thereby operating the plasma arc torch in a second mode to deliver gas and electric power to the plasma arc torch. Furthermore, the selector may comprise a neutral position such that delivery of gas and electric power to the plasma arc torch is inhibited.
In yet another form of the present invention, a housing is provided that is disposed within a trigger system of a plasma arc torch. A selector is disposed within the housing and is operable between at least a first operating position and a second operating position, and preferably a neutral position, wherein the first and second operating positions activate the gas and electric power, respectively, and the neutral position inhibits delivery of the gas and electric power as previously described.
In another form, the present invention provides a selector for use in a trigger system of a plasma arc apparatus that is operable between a first operating position, a second operating position, and a neutral position as previously described. The selector preferably comprises a post to limit operation of the trigger system such that delivery of gas and electric power to the plasma arc torch is inhibited. Additionally, the selector comprises an engagement member that activates a power switch disposed within the plasma arc torch to provide the gas and the electric power.
The present invention also provides methods of operating a plasma arc torch among one or more of a first operating mode wherein gas is delivered to the plasma arc torch, a second operating mode wherein gas and electric power are delivered to the plasma arc torch, and a neutral mode wherein delivery of gas and electric power to the plasma arc torch is inhibited.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.